How Metallica lose themselves in the music

Metallica is in the middle of a year-and-a-half-long world tour, covering 96 shows across the Americas, Asia, and Europe. The WorldWired Tour is the band's first North American tour in eight years, and their first stadium tour in 20 years. It's a monumental production, pushed forward on the momentum 110 million albums sales since their debut in 1983. The huge stage takes three days to build, but each show starts in a small room, just big enough for a drum kit, three microphones, and a couple of sound monitors. About an hour before each show, Metallica gathers in what they call the "tuning room", somewhere deep in the bowels of the stadium, to knock the rust off and check in with each other.

For a metal behemoth, it is their way of returning to the very essence of a garage band: four guys packed into a tight space, jamming, goofing off, and mugging for their friends. For Metallica, this time is also used to go over some of the deep cuts that vary from show-to-show.

"We change the set list a lot," Lars told "CBSN: On Assignment." "We never play the same list twice, so we'll always warm up on a couple of the songs we haven't played for maybe a couple of weeks."

Lars creates the set list for each show, a process that has become surprisingly scientific. "I get all the statistics of every time we played in Detroit in the last 10-to-15 years. What songs did we play there of the deeper cuts? And then I make sure that we don't play the same ones."

Even in the biggest stadium, Metallica kicks off in a tiny warm-up room

One of the few songs that remains a live show staple is "Master of Puppets." It is a fast, melodic, and complex nine-minute song that guitarist Kirk Hammett gets completely lost in.

"I get so wrapped up in what I'm playing and how I'm playing it — the execution of it — that oftentimes I forget the audience is out there. It's crazy. And only sometimes over the course of a show that might happen, but I'm snapped back and I'm aware of the audience again."

For frontman and lyricist James Hetfield, he's always aware of how the audience is absorbed by the audience. "Deep down knowing that someone understands what I'm writing, that is very connecting," he said. "When I, especially as a youth, felt very alienated, very angry. For 60,000 people to be singing along with what craziness was in my head. It's very connecting. And, I can't explain it. It's a feeling of belonging. It's a feeling of purpose. It's a feeling of connection."

From the back of the stage, drummer Lars Ullrich still feels a deep connection with the audience. "Whether there's 45,000 people, 450 people, or four people in your backyard, if we can find a way for the band and the audience to connect, and feel as one, then we've achieved our primary goal."

But how can you possibly do that in an outdoor stadium with fans packing every last corner of the upper deck? "I call it the thousand-yard stare," Lars said. "You have to include everybody. You look out. You try to embrace. You bring people closer."